1. Field of the Invention
The present invention relates generally to medical devices and methods. More particularly, the invention relates to methods and devices for locating and treating uterine fibroids.
There are unmet needs in the pathophysiology of the female reproductive tract, such as dysfunctional uterine bleeding and fibroids. Fibroids are benign tumors of the uterine myometria (i.e., muscle) and are the most common tumor of the female pelvis. Fibroid tumors affect up to 30% of women of childbearing age and can cause significant symptoms such as discomfort, pelvic pain, mennorhagia, pressure, anemia, compression, infertility and miscarriage. Fibroids may be located in the myometrium (i.e., intramural), adjacent to the endometrium (i.e., submucosal), or in the outer layer of the uterus (i.e., subserosal). Most commonly fibroids are a smooth muscle overgrowth that arise intramurally and can grow to be several centimeters in diameter.
Current treatment for fibroids includes medical treatment with NSAIDS, estrogen-progesterone combinations, and GnRH analogues. Pharmacologic therapy with GnRH analogues is limited due to its side effects, such as hot flashes, vaginal dryness, mood changes and bone density loss. Further, its relatively short time of treatment (e.g., 3 months) offers temporary shrinkage, wherein the fibroids usually regrow after medical discontinuation. Pharmacologic therapy is relatively ineffective and palliative rather than curative.
Hysterectomy (i.e., surgical removal of the uterus) is a common treatment for fibroids. It is performed up to 600,000 times annually in the United States. Indeed, fibroids are the indication for hysterectomy in up to one third of all cases. Hysterectomy for treating fibroids may be very effective but has many undesirable side effects such as loss of fertility, open surgery, sexual dysfunction, and long recovery time. There is also significant morbidity (e.g., sepsis, hemorrhage, peritonitis, bowel and bladder injury), mortality, and costs associated with hysterectomy treatments.
Surgical myomectomy is also an open surgical procedure requiring laparotomy and general anesthesia in which fibroids are removed. Often these procedures result in significant blood loss and can only remove a portion of the culprit tissue. In the early 1990's there was a growth in advanced operative laparoscopy techniques and laparoscopic myomectomy was pioneered. However, laparoscopic myomectomy remains technically challenging. For example, it requires laparoscopic suturing which is performed only by the most skilled of laparoscopic gynecologists. Further, prolonged anesthesia time, increased blood loss, and possibly higher risk of uterine rupture in pregnancy make laparoscopic myomectomy a challenging procedure. Currently, the removal of subserosal or intramural fibroids requires an abdominal approach.
Hysteroscopy (i.e., process by which a thin fiber optic camera is used to image inside the uterus) may include an attachment to destroy tissue. Hysteroscopic resection is a surgical technique that uses a variety of devices (e.g., loops, roller balls, bipolar electrodes) to ablate or resect uterine tissue. The uterus needs to be filled with fluid for better viewing and thus has potential side effects of fluid overload. Hysteroscopic ablation is also limited by its visualization technique and is thus only appropriate for those fibroids that are submucosal and/or protrude into the uterine cavity.
Uterine artery embolization has also been suggested as an alternative minimally invasive treatment for fibroids. Uterine artery embolization was introduced in the early 1990's and is performed by injecting small particles through a groin incision into the uterine artery to selectively block the blood supply to fibroids. Uterine artery embolization results in reduction of the myoma size from 20-70% at six months. However, side effects of this procedure include pelvic infection, premature menopause, and severe pelvic pain. In addition, long term MRI data suggest that incomplete fibroid infarction may result in regrowth of infracted fibroid tissue. Despite much interest in uterine artery embolization, the procedure rates remain low and have not grown past a few thousand performed per year in the United States. This may be due to the fact that interventional radiologists, instead of gynecologists who know how to diagnose and treat fibroid tumors, are the ones who perform uterine artery embolization procedures.
Endometrial ablation, which is primarily a procedure for dysfunctional or abnormal uterine bleeding, may be used at times for fibroids. Recently there have been many new technologies to perform endometrial ablation such as cryo energy, microwave energy, and impedance controlled radiofrequency. Endometrial ablation destroys the endometrial tissue lining the uterus, but does not specifically treat fibroids. This technique is also not suitable for women who desire to bear children. Endometrial ablation remains a successful therapy for dysfunctional uterine bleeding, but is limited in its ability to treat fibroids.
Myolysis is another alternative minimally invasive technique for fibroid treatment. Myolysis was first performed in the 1980's in Europe by using lasers to coagulate tissue, denature proteins, and necrose myometrium with laparoscopic visualization. This technique has been in use for the past several years and involves applying energy directly to the myoma. Laparoscopic myolysis can be an alternative to myomectomy, as the fibroids are coagulated and then undergo coagulative necrosis resulting in a dramatic decrease in size. Shrinkage of fibroids has been reported at 30-50%. In addition there is the obvious economic benefit of out-patient surgery, rapid recovery, and return to normal lifestyle. However, all laparoscopic techniques are limited by the fact that they can only see, and therefore only treat, subserosal fibroids.
Needle myolysis is a promising technique whereby a laparoscope is used to introduce one or more needles into a fibroid tumor under visual control. Bipolar radiofrequency current is then delivered between two adjacent needles, or monopolar current between a single needle and a distant dispersive electrode affixed to the thigh or back. The aim of needle myolysis is to coagulate a significant volume of the tumor and thereby cause it to shrink substantially. The traditional technique is to make multiple passes through different areas of the tumor using the coagulating needle to destroy many cylindrical cores of abnormal tissue. However, the desirability of multiple passes is mitigated by the risk of adhesion formation, which is thought to increase with increasing amounts of injured uterine serosa and by the operative time and skill required.
For these and other reasons, it would be desirable to provide a minimally invasive method and device to selectively eradicate fibroid tumors within the uterus. It would be desirable if the method and device could locate and treat all types of fibroids in the uterus in a safe and effective manner with minimum risk and discomfort for the patient. It would be further desirable to provide a method and device for eradicating fibroid tumors that combines imaging and treatment in one simple hand held device. At least some of these objectives will be met by the methods and devices of the present invention described hereinafter.
2. Description of the Background Art
Relevant references include U.S. Pat. No. 5,456,689 Kresch et al.; U.S. Pat. No. 5,979,453 Savage et al.; U.S. Pat. No. 6,002,968 Edwards; U.S. Pat. No. 6,550,482 Burbank et al.; U.S. Pat. No. 6,626,855 Weng et al.; U.S. Pat. No. 6,716,184 Vaezy et al.; WO 2004/064658; and US 2005/0107781. The full disclosures of each of the above references are incorporated herein by reference.